Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS4865792 A
Publication typeGrant
Application numberUS 07/153,544
Publication dateSep 12, 1989
Filing dateFeb 2, 1988
Priority dateJun 22, 1987
Fee statusLapsed
Publication number07153544, 153544, US 4865792 A, US 4865792A, US-A-4865792, US4865792 A, US4865792A
InventorsJames D. Moyer
Original AssigneeMoyer James D
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Method of using composite reinforced grommet
US 4865792 A
Abstract
A device and method to prevent delamination at load-bearing apertures in structural composite substrates is disclosed. The device is a composite reinforcing grommet having a hollow, generally tubular member of braided filaments impregnated with polymer. The member may be radially deformed for insertion into an aperture in a structural composite substrate and is then capable of being radially expanded to form flanges to secure the structural composite between the flanges. A method of reinforcing a substrate having an aperture therethrough including the step of cobonding a composite reinforcing grommet to a structural composite substrate is also disclosed.
Images(2)
Previous page
Next page
Claims(9)
What is claimed is:
1. A method of reinforcing a substrate having an aperture therein, comprising the steps of:
(a) providing a composite reinforcing grommet comprising a hollow generally tubular member of braided filaments, said filaments being impregnated with a polymeric material, said member having a central body portion and opposite end portions, said braided filaments allowing said member to be generally radially deformable, one or both of said end portions capable of being radially expanded to form flanges;
(b) providing a substrate which comprises a polymeric material and which has an aperture therein;
(c) inserting said member into said aperture;
(d) expanding at least one of the end portions of the member radially outward to form a flange which cannot be drawn through said aperture; and
(e) while the polymeric materials of both the substrate, at least in the vicinity of the apertures, and the grommet are soft, curing the said polymeric materials while applying pressure thereto so that a bond is formed between the substrate and the grommet.
2. A method as claimed in claim 1, in which at least one of the polymeric materials is a thermoplastic material, and the method includes the step of applying heat to the or each thermoplastic material to cause it to soften, after insertion of the tubular member into the aperture, and in which the or each thermoplastic polymeric material is made to cure by cooling below its crystalline temperature.
3. A method as claimed in claim 2, in which the polymeric materials of the substrate, at least in the vicinity of the aperture, and of the grommet, are both thermoplastic materials.
4. A method as claimed in claim 1, in which at least one of the polymeric materials is a thermosetting material.
5. A method as claimed in claim 4, which includes the step of applying heat to the or each thermosetting polymeric material to cause it to cure.
6. A method as claimed in claim 1, which includes the step of supporting the internal surface of the tubular member to control deformation thereof during formation of the flange.
7. A method as claimed in claim 1, in which one of the end portions of the tubular member is expanded prior to insertion of the tubular member into the aperture.
8. A method as claimed in claim 1, in which more than one of the end portions of the tubular member is expanded outwardly so as to form flanges which cannot be drawn through said aperture, the substrate being restrained between two flanges.
9. A method as claimed in claim 1, in which the tubular member is inserted in registered apertures in two such substrates so as to join the substrates to one another after the polymeric materials have cured.
Description

This application is a continuation of application Ser. No. 061,607, filed June 22, 1987, now abandoned, which is a continuation of application Ser. No. 904,854, filed Sept. 8, 1986, now abandoned, which is a continuation of application Ser. No. 757,057, filed July 19, 1985, now abandoned.

BACKGROUND OF THE INVENTION

This invention relates to structural composite laminates and the problem of preventing delamination at load-bearing apertures in such structural components.

The structural integrity of composite laminates is severely compromised when such laminates are drilled or cut such as for purposes of attachment. An aperture in such a laminate tends to especially compromise the axial or Z-axis integrity of the laminate and provides a site for delamination of the composite laminate.

In high-performance applications such as aerospace structures a typical composite may consist of a mat of interwoven high modulus filaments impregnated with a polymer. The drilling of such a laminate to provide an aperture destroys the continuity of the structural filaments contained within the composite. Conventional metal fasteners inserted into such apertures are unsuitable for attachment purposes. The difference in thermal coefficient of expansion of the materials of the composite and the fasteners as well as the differences in hardness will eventually destroy the laminate. The instant invention provides a composite reinforcing grommet of materials similar to that of the composite laminate, thus avoiding thermal expansion problems. Such a grommet is further capable of being co-bonded to the composite material. The polymer impregnated braided filaments of such grommets are capable of being radially expanded to form flanges to secure composite laminates therebetween and thus provide axial or Z-axis integrity. The grommet then provides a suitable attachment mechanism for conventional fasteners.

SUMMARY OF THE INVENTION

The purpose of the instant invention is to provide axial or Z-axis integrity to composite laminates to prevent delamination at load-bearing apertures in such composite laminates. To accomplish this purpose the instant invention provides a composite reinforcing grommet having a hollow generally tubular member of braided filaments impregnated with a polymer, said member capable of being radially deformed when necessary for insertion into a substrate and for subsequent expansion to create flanges outside of such a substrate. Specifically, there is provided a composite reinforcing grommet comprising a hollow generally tubular member braided filaments, said filaments being impregnated with polymer, said member having a central body portion and opposite end portions, said braided filaments allowing said member to be generally radially deformable, said end portions capable of being radially expanded to form flanges to secure a substrate to be reinforced between said flanges.

Another aspect of the invention is a method of reinforcing a substrate having an aperture therethrough comprising the steps of:

providing a composite reinforcing grommet comprising a hollow generally tubular member of braided filaments, said filaments being impregnated with a polymer, said member having a central body portion and opposite end portions, said braided filaments allowing said member to be generally radially deformable, said end portions capable of being radially expanded to form flanges to secure a substrate to be reinforced between said flanges;

providing a substrate having an aperture therethrough;

inserting said member into said aperture; and,

expanding the end portions of the member radially outwardly to form flanges, said substrate being secured between said flanges, said aperture being reinforced radially and axially by the grommet.

DESCRIPTION OF THE DRAWING

FIG. 1 is a perspective view of a composite laminate having an aperture therethrough with the composite reinforcing grommet of the instant invention positioned adjacent thereto.

FIG. 2 is a cut-away perspective view as in FIG. 1 after insertion of the grommet into the aperture.

FIG. 3 is a cut-away perspective view as in FIG. 2 wherein the grommet has been inserted through the aperture and the end portions of the grommet have been expanded to form flanges. Also illustrated in this figure is a hole size plug and a locator/size pin which may alternatively be placed within the hollow confines of the grommet during a sizing and/or curing process step.

FIG. 4 is a perspective view of the grommet of the instant invention partially in phantom prior to insertion in a substrate comprising two laminates separated by a core material.

FIG. 5 is a perspective view as in FIG. 4 after flaring of the end portions (in phantom) of the grommet.

DESCRIPTION OF THE PREFERRED EMBODIMENT

With continued reference to the drawing wherein like parts are designated by the same reference numerals, FIG. 1 illustrates the composite reinforcing grommet shown generally at 10 prior to insertion into an aperture 12 in a substrate in the form of composite laminate 14 in the form of a pre-preg laminate. Grommet 10 comprises a hollow generally tubular member 16 of braided filaments 18, said filaments being impregnated with a polymer 20. Grommet 10 may therefore be generally called a pre-preg insert sleeve. In the preferred embodiment of the invention the polymers of the substrate and the grommet are compatable so that the grommet may be preferably co-bonded to the substrate. As used herein the terms grommet and member are used interchangeably.

Included within the concept of generally tubular are configurations for member 16 other than purely cylindrical, such as tapered or convoluted shapes (not shown). These configurations are useful for ease of insertion or for such purposes as temporary location or holding of the member during installation.

Member 16 has a central body portion 22 and opposite end portions 24 and 26. Since the filaments 18 are braided the member 16 is capable of being generally radially deformable. As shown in FIG. 1, end portion 26 has been radially pre-expanded to form a flange which is perpendicular to the longitudinal axis of the member 16. Member 16 is also shown to be slightly larger in diameter than aperture 12 to illustrate that the member 16 may also be radially deformable inwardly for insertion into a smaller diameter aperture 12.

FIG. 1 therefore illustrates the composite reinforcing grommet of the instant invention and the first step of providing reinforcing to a substrate having an aperture therein and providing a grommet.

FIG. 2 illustrates the grommet 10 of the instant invention after insertion into composite laminate 14. This may be accomplished by hand or by the aid of special tools well known to those skilled in the art. As mentioned earlier the grommet may, if necessary, be radially compressed by such tools for insertion into a smaller diameter aperture. A portion of the composite laminate 14 has been cut-away for illustration purposes to show central body portion 22 and end portions 26 and 24. It can be seen that end portion 24 has been partially expanded radially outwardly.

FIG. 2 therefore illustrates a cut-away view of the grommet of the instant invention after insertion into a composite laminate and illustrates the step of insertion of the grommet into the aperture of such a composite laminate.

FIG. 3 illustrates the grommet 10 after it has been inserted through the opening after the end portion 24 has been fully expanded radially outwardly to create a flange generally perpendicular to the axis of the member or grommet which will lie flat against the side of the laminate 14. Likewise, flange 26 lies flat against the other side of the laminate. In order to maintain inside radial dimensions, i.e., accurate hole size of the grommet, a retraining mandrel in the form of a hole size plug 28 may be inserted, as noted, within the hollow confines 30 of the member 16. In the alternative, a locator/size pin 32 may be inserted for purpose of restraining within the member 16. The use of plugs or pins applies especially to embodiments of the instant invention wherein the polymer is a thermosetting material which should be restrained during cure. It is also within the scope of the invention to use a heated tool incorporating a plug or pin when a thermoplastic material is used for the resin 20. FIG. 3 therefore illustrates the grommet of the instant invention after insertion and flanging and specifically the method steps of expanding and co-bonding the end portions of the member against both side of the laminate and of the curing of the polymer of the grommet such as by pressure and/or temperature to co-bond at least the end portions to the laminate. FIG. 3 also illustrates the step of restraining the inside dimension of the member by the use of a mandrel-like member.

FIG. 4 illustrates the grommet of the instant invention when used as a tie-rod or a Z-axis composite hole support. Specifically, the figure illustrates a substrate comprised of two laminates 14 separated by a core 34. A composite reinforcing grommet 10 in the form of a generally tubular member is positioned prior to insertion into the aperture 36 of the substrate. Aperture 36 is preferably a chamfered hole or aperture both for the purpose of guidance and for stress-relieving the composite reinforcing grommet 10 and the laminates.

FIG. 5 illustrates the grommet after installation wherein end portions 24 and 26 (26 shown in phantom line) have been flared to form co-bonding flanges with respect to composite laminates 14.

The composite reinforcing grommet has been described as a tubular member of braided filaments which have been impregnated with polymer and have been generally referred to as a pre-preg braided insert sleeve. By way of example, but not limitation, typical filament materials used for this structure are glass, and high modular materials such as carbon graphite, boron and Kevlar* material. Other filament materials and combinations thereof, either in individual filaments or in braided combined configuration are within the scope of the invention.

Polymers that are used for impregnation of the braided filaments may be either thermosetting or thermoplastic polymers. By way of example, but not limitation, typical polymers include epoxy resins, polyethylene, polypropylene, nylons, etc.

The foregoing detailed description is illustrative of the embodiments of the invention. Variations and modifications will be apparent to those skilled in the art within the scope of the appended claims.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US586770 *Jul 20, 1897 Eyelet
US1640543 *Nov 28, 1919Aug 30, 1927Westinghouse Electric & Mfg CoBushing and method of forming the same
US2510693 *Mar 29, 1944Jun 6, 1950Lee B GreenFastening member
US2584540 *Jan 27, 1950Feb 5, 1952Botvin Irving EColostomy pouch
US4478544 *Jun 4, 1982Oct 23, 1984Microdot Inc.Composite rivet
NL6612117A * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4983240 *Apr 26, 1989Jan 8, 1991Kamatics CorporationMethod of making a flanged braided bearing
US5377658 *Mar 29, 1993Jan 3, 1995Precision Shooting Equipment, Inc.Reinforcement for bow limb
US5437750 *Apr 8, 1994Aug 1, 1995Fokker Special Products B.V.Method for securing a thermoplastic insert
US5536344 *Sep 13, 1994Jul 16, 1996Shur-Lok CorporationMethod of installing a plastic composite fastener in a panel
US5726392 *Feb 21, 1997Mar 10, 1998Communications Technology CorporationCommunications housing having grommet assembly
US6153035 *Feb 12, 1999Nov 28, 2000The Boeing CompanyMethod and apparatus for securing a thermoplastic insert within a sandwich panel
US6375120Mar 9, 2000Apr 23, 2002Jason M. WolnekMethod and apparatus for building a metal/composite hybrid airplane component
US7047596 *Dec 9, 2003May 23, 2006Sikorsky Aircraft Corp.Structural bushing application for highly loaded composites lugs
US7150594 *Mar 9, 2004Dec 19, 2006The Boeing CompanyHybrid fastener apparatus and method for fastening
US7384226 *Apr 15, 2004Jun 10, 2008Newfrey LlcBlind fastener
US7731164 *Nov 25, 2005Jun 8, 2010Valeo Systemes D'essuyageVibration damper device comprising a flange ring capable of coming to a stop against a damper unit
US7784585 *Apr 5, 2005Aug 31, 2010Acs Industries, Inc.Wire mesh heat shield isolator
US7878744 *May 9, 2007Feb 1, 2011Nd Industries, Inc.Fibrous microencapsulated washer for fasteners
US8393068 *Nov 6, 2007Mar 12, 2013The Boeing CompanyMethod and apparatus for assembling composite structures
US8474759Aug 10, 2009Jul 2, 2013The Boeing CompanyMethod and apparatus for fastening components using a composite two-piece fastening system
US8870510Nov 19, 2009Oct 28, 2014Acs Industries, Inc.Wire mesh rivet
US8993090 *Jan 5, 2012Mar 31, 2015Airbus Operations (S.A.S.)Part for and method of repairing a damaged structure, in particular an airframe skin, and a repair kit for implementing it
US9555466 *Mar 1, 2012Jan 31, 2017Nihon UniversitySubstrate joining method using rivet, and joining structure
US20040228706 *Apr 15, 2004Nov 18, 2004Jones Steven V.Blind fastener
US20050125946 *Dec 9, 2003Jun 16, 2005Steve SucicStructural bushing application for highly loaded composites lugs
US20050201845 *Mar 9, 2004Sep 15, 2005The Boeing CompanyHybrid fastener apparatus and method for fastening
US20060062650 *Sep 20, 2004Mar 23, 2006The Boeing CompanyHybrid fastener apparatus and method for fastening
US20060219860 *Apr 5, 2005Oct 5, 2006Acs Industries, Inc.Wire mesh heat shield isolator
US20070292241 *May 9, 2007Dec 20, 2007Snow Gerald FFibrous microencapsulated washer for fasteners
US20080041734 *Sep 22, 2006Feb 21, 2008Bergelson Alan PJewelry display apparatus
US20090019657 *Nov 25, 2005Jan 22, 2009Valeo Systemes D'essuyageVibration Damper Device Comprising A Flange Ring Capable Of Coming To A Stop Against A Damper Unit
US20090126180 *Nov 6, 2007May 21, 2009Keener Steven GMethod and apparatus for assembling composite structures
US20100001137 *Aug 10, 2009Jan 7, 2010The Boeing CompanyMethod and Apparatus for Fastening Components Using a Composite Two-Piece Fastening System
US20100119299 *Nov 30, 2009May 13, 2010Sgl Carbon SeComposite fastener for ceramic components
US20120177878 *Jan 5, 2012Jul 12, 2012Airbus Operations (S.A.S.)Part For And Method Of Repairing A Damaged Structure, In Particular An Airframe Skin, And A Repair Kit For Implementing It
US20120272637 *Apr 28, 2011Nov 1, 2012Brian Kenneth HollandReplacing an aperture in a laminated component
US20130340239 *Mar 1, 2012Dec 26, 2013Nihon UniversitySubstrate joining method using rivet, and joining structure
US20150050453 *Mar 22, 2013Feb 19, 2015Cutting Dynamics, Inc.Injection molded composite blank and guide
DE19506933A1 *Feb 28, 1995Sep 5, 1996Daimler Benz AgCase placed in screw holes for securing plastic parts to a metal support
DE102012001057A8 *Jan 20, 2012Mar 13, 2014Liebherr-Aerospace Lindenberg GmbhBauteil
DE102013209635A1 *May 24, 2013Nov 27, 2014Schaeffler Technologies Gmbh & Co. KgKorrosionsgeschützte Bohrung
DE112006000808B4 *Apr 5, 2006Aug 20, 2015Acs Industries, Inc.Drahtgeflecht-Hitzeschildisolator
EP1136139A2 *Mar 7, 2001Sep 26, 2001Saint-Gobain Vetrotex FranceProcess for sealing off a bare section of the wall of a tubular article composed of reinforced thermoplastics material
EP1136139A3 *Mar 7, 2001Feb 4, 2004Saint-Gobain Vetrotex FranceProcess for sealing off a bare section of the wall of a tubular article composed of reinforced thermoplastics material
EP1839802A2 *Mar 16, 2007Oct 3, 2007United Technologies CorporationFabric bushing installation to repair a hole
EP1839802A3 *Mar 16, 2007Jun 30, 2010United Technologies CorporationFabric bushing installation to repair a hole
EP2439051A1 *Jun 9, 2011Apr 11, 2012Bayerische Motoren Werke AktiengesellschaftCorrosion protection for a perforated piece of sheet metal
EP2517865A1 *Apr 27, 2012Oct 31, 2012United Technologies CorporationReplacing an aperture in a laminated component
WO2006108046A2 *Apr 5, 2006Oct 12, 2006Acs Industries, Inc.Wire mesh heat shield isolator
WO2006108046A3 *Apr 5, 2006Jun 11, 2009Acs Ind IncWire mesh heat shield isolator
WO2008036983A2 *Sep 24, 2007Mar 27, 2008Bergelson Alan PJewelry display apparatus
WO2008036983A3 *Sep 24, 2007Dec 11, 2008Alan P BergelsonJewelry display apparatus
WO2010062828A1 *Nov 19, 2009Jun 3, 2010Acs Industries, Inc.Wire mesh rivet
Classifications
U.S. Classification264/249, 264/137, 29/512, 411/908, 411/258, 264/136, 29/522.1, 156/92, 411/901, 264/257, 156/293, 411/34
International ClassificationB29C70/88, B29C65/60, F16B43/00, F16B5/02, B29C63/00, F16B5/01
Cooperative ClassificationF16B43/00, B29L2031/71, B29C66/474, B29C65/602, B29C66/73751, B29C66/73941, B29C66/73921, B29C66/8322, B29C66/7394, B29C66/7212, B29C66/71, B29C66/7392, Y10T29/49938, Y10T29/4992, Y10S411/908, Y10S411/901, F16B5/02, B29C63/0082, F16B5/01, B29L2031/737, B29C70/887
European ClassificationB29C65/60B2, F16B5/02, B29C63/00V, F16B5/01, B29C70/88B, F16B43/00
Legal Events
DateCodeEventDescription
Mar 20, 1989ASAssignment
Owner name: RAYCHEM CORPORATION, A CORP. OF CA
Free format text: MERGER;ASSIGNORS:RAYCHEM CORPORATION, A CORP. OF CA (MERGED INTO);MEHCYAR CORPORATION, A DE CORP. (CHANGED TO);REEL/FRAME:005175/0324;SIGNING DATES FROM 19870129 TO 19870729
Owner name: BENTLEY-HARRIS MANUFACTURING COMPANY, THE, A CORP.
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:RAYCHEM CORPORATION, A DE. CORP.;REEL/FRAME:005073/0623
Effective date: 19890331
Feb 22, 1993FPAYFee payment
Year of fee payment: 4
Mar 22, 1996ASAssignment
Owner name: BENTLEY-HARRIS INC., PENNSYLVANIA
Free format text: CHANGE OF NAME;ASSIGNOR:BENTLEY-HARRIS MANUFACTURING CO., THE;REEL/FRAME:007846/0539
Effective date: 19950929
Apr 22, 1997REMIMaintenance fee reminder mailed
Sep 14, 1997LAPSLapse for failure to pay maintenance fees
Nov 25, 1997FPExpired due to failure to pay maintenance fee
Effective date: 19970917